The present invention relates to selection of a preferred network for roaming and, more particularly, but not exclusively to a method or system for blocking network selection redirection attempts in roaming.
There are many mobile or cellular network operators, or providers, in the world, usually more than one in a single country. These network operators include, but are not limited to, operators who provide mobility services using GSM, GPRS, 3G, CDMA, TDMA, PHS, WCDMA, IDEN and WLL technologies or their variants. These network operators provide voice and data services to their own subscribers and to subscribers from other networks. When the network operator provides service to a subscriber from a foreign country, it is referred to as “international roaming”. When the network operator provides service to a subscriber from another network in the same country, it is referred to as “domestic roaming”.
A cellular network with which a cellular subscriber has a direct billing relationship is often referred to as the Home Public Mobile Network (HPMN) or as the home network of the subscriber. If the subscriber is in a network with which it does not have a direct billing relationship, the serving network is referred to as the Visited Public Mobile Network (VPMN) or as the visited network. The subscriber is referred to as an in-roamer by the VPMN. The same subscriber is referred to as an out-roamer by the HPMN. In such a case, the in-roamers are treated as temporary subscribers from a service availability perspective, while the billing for usage incurred by them is through inter-carrier settlements via the home network of the subscriber.
Over the last few years, the revenues to network operators from home subscribers have consistently declined due to increased competition and resultant pricing pressures. On the other hand, revenues from roamers have consistently grown in the same period due to increased mobile penetration in local markets and an increase in travel. Moreover, roaming revenues are high-margin revenues that typically comprise between 8-25% of the total network operator revenues. Hence, protecting the existing roaming revenues and growing them further has become an important priority for the network operators worldwide.
VPMN operators, aware of the growing significance of in-roamer revenues for their profitability, make their best to protect and further grow their share of roaming revenues, gained from in-roaming in their service covered areas. An in-roamer himself may also have his own preferences, based on attractive roaming rates, availability of services, etc.
HPMN operators have preferences with regards to different VPMNs to be used by their subscribers when roaming abroad. Many network operators have partnership agreements with each other that include more favorable roaming charges between then. Some operators also own or are business-grouped with networks in various countries. These operators would like to make sure their out-roamers stay within the group, or roam in preferred networks.
There are currently some products in the mobile cellular market which help HPMN operators redirect network selection of roaming mobile cellular phones. Such products are offered, for example, by StarHome Inc.
These products are typically based on the idea that a system deployed in association with the HPMN (the home network) is used to issue various rejection messages m response to registration attempts of roamers trying to register to a VPMN which is not preferable as far as the operator of the HPMN is concerned. Such a rejection message causes a mobile unit/handset in an automatic network selection mode to search for another network. The other network may also be rejected by the HPMN using such rejection messages, and so forth, until a HPMN preferred network is found.
In GSM networks, these products monitor and optionally reject update location SS7/MAP messages that are used as registration messages to the VPMN, sent to the HPMN from the mobile unit. The product may be based on a monitor or probe placed on the SS7/MAP signaling lines.
Alternative products send a list of available networks in order of preference to the individual handset. The list is typically provided by Over the Air SIM update and is combined with a SIM applet. The list is used by the handset to search for available VPMNs in order. Reference is now made to FIG. 1, which is a block diagram illustrating the deployment of a unit for network redirection, in the HPMN side, according to prior art.
In an exemplary deployment of a prior art redirection unit, a redirection unit 120 may be deployed in the home network (HPMN) of the mobile unit. The redirection unit may comprise a probe part 130.
The probe part 130 picks up passing signals to carry out detection of roaming activity by mobile units, such as unit 140, in a roaming environment 150, such as a foreign country to which home network 110 does not extend.
The home network 110 is the network which the roaming unit 140 is subscribed to. The roaming environment 150 includes a number of mobile networks, VPMN 1-3 in this example, which are technologically compatible with the roaming mobile unit 140 and which the roaming mobile unit 140 may use.
The home network 110 may have preferences over the VPMNs, for example, the home network 110 may prefer a network which belongs to the same parent company. Utilizing the redirection unit 120, the home network 110 may attempt to manipulate the mobile unit 140 into selecting a network which it regards as preferable.
The redirection unit 120 may send a manipulative output, through an output port 190. The manipulative output may include a rejection message sent in response to the detected roaming activity for a non-preferred network, say VPMN 1 in the given example. Upon a predetermined number of attempts to roam in VPMN 1, the mobile unit 140, in an automatic network selection mode, automatically searches for another network, until finding a second available network, say VPMN 2.
The second network may also be non-preferable as far as the home network 110 is concerned, and the redirection unit 120 may redirect the mobile unit 140 from this network as well, and so forth until a network which is preferable to the home network is finally reached (VPMN 3 in the given example), thus successfully completing a redirection of the roaming mobile unit 140.
Reference is now made to FIG. 2 which is a flow chart illustrating an exemplary redirection process, in a GSM environment, by the home network (HPMN), according to prior art.
When a visited network (VPMN) network communication base station receives a registration message—an update location (UL) MAP message from the mobile handset 210, trying to roam in the VPMN, the message is forwarded to a Visitors Location Register (VLR) 220, which is a local database maintained by the VPMN to track visiting mobile unit users while the users are roaming in the VPMN.
The HPMN is communicated with the update location message 230, for registering the location of the mobile unit in a HLR—The main database of permanent subscriber information for the HPMN.
A responding rejection message is then sent 240 to the VLR in the VPMN from a Home Location Register (HLR) of the HPMN, or from a redirection system, emulating the HLR for this purpose, which is deployed in the HPMN.
The rejection message is then forwarded to the mobile unit (MU) 250.
The mobile unit/handset (MU), in an automatic network selection mode, is preconfigured by standard to automatically issue a preset standard number of attempts to register for the visited network by repetitive sending of the UL message for the VPMN to the home network 260.
According to a GSM standard, a mobile unit is preconfigured to issue four such registration attempts, and then search for another network. The reason for this is that users have the facility to hand-pick the desired network. The standard requires providers to honor the handmade selections of the users.
The home network thus manipulatively rejects these UL messages, and the mobile unit is maneuvered to search for another VPMN network in this successful redirection 290. A second found VPMN, in its turn, may also be rejected by the HPMN, and so forth until a HPMN preferred network is finally found.
As mentioned above, handsets are provided with a mode in which the user is able to manually select a network. In this manual mode, the mobile unit/handset shows a list of available networks to the user. The user selects one of the available networks and the handset attempts registration onto that network. If the registration is not successful, the handset waits for a predetermined delay and tries again. According to a GSM standard, in non-manual modes the number of retries is limited to four, so that a fifth retry may be recognized as manual mode. However, if specific handsets are configured to a different number of retrials than four, say five, the HPMN system may be configured accordingly, say to six, for this type of handsets. In manual mode, the user himself has selected a particular network, so preferred VPMN selection from the HPMN perspective should not apply and the HPMN deployed redirection unit is expected to honor the will of the handset user.
However, a majority of current handsets are kept in automatic selection mode as the manual mode is not known to most users, and the HPMN is keen on controlling or influencing the selection of a VPMN.
In any event, with the deployment of such network selection systems at the HPMN, both the operator of the VPMN and the roaming user are left dependent on the HPMN systems when trying to exercise fair competition and the freedom to choose among different networks.
There is thus a widely recognized need for, and it would be highly advantageous to have, a system or method for the selection of a preferred network for roaming which is devoid of the above limitations.